Abstract 90: Comparison of 15:1, 15:2, and 30:2 Compression-Ventilation Ratios for Cardiopulmonary Resuscitation in an Animal Model of a Simulated, Witnessed Cardiac Arrest
Objective: This study was performed to compare the effects of cardiopulmonary resuscitation (CPR) with various compression-to-ventilation (C:V) ratios on the hemodynamics, the arterial oxygen profiles, and the delivery of CPR.
Subjects and methods: After induction of ventricular fibrillation, thirty dogs were randomized to a C:V ratio of 15:1, 15:2, or 30:2. To simulate a witnessed cardiac arrest with bystander CPR, CPR was started 1 minute after induction of ventricular fibrillation and continued for 4 minutes. Manual CPR was performed by expert rescuers with a simulated scenario of a witnessed cardiac arrest. The hemodynamics and the arterial blood gases were measured during CPR and after restoration of spontaneous circulation (ROSC).
Results: During basic life support (BLS) and advanced cardiac life support (ACLS) CPR, there were no significant differences in the hemodynamics (systolic and diastolic blood pressure, coronary perfusion pressure, total coronary perfusion gradient, or carotid blood flow) between the three groups. In groups with the ratios 15:1 and 30:2, compressions delivered over 1 min were significantly greater than the group with a ratio 15:2 (73.1±8.1 and 69.0±6.9 to 56.3±6.8; p=0.000). Interruptions of chest compression were significantly reduced the 15:1 and 30:2 groups (15.4±3.9 and 17.1±2.7 to 25.2±2.6 secs/min; p=0.000). Arterial blood gases, including PaO2, PaCO2, and oxygen saturation, were not significantly different between the three groups. Eight of 10 animals from each group achieved ROSC during BLS and ACLS.
Conclusion: In an animal model of a simulated, witnessed cardiac arrest, CPR with C:V ratios 15:1 and 30:2 delivered more compressions over 1 min than that with a C:V ratio of 15:2. There were no significant differences in the hemodynamics, and the ROSC rate between 3 groups during BLS and ACLS CPR.